Red Blood Cell Production



Video Topic : Red blood cell production or erythropoiesis is the process by which red blood cells are formed.

In early development, RBC production begins in the yolk sac, shifts to the liver and spleen during the 3rd month of gestation, and finally to the bone marrow in the 5th month. Once adulthood is reached, the creation of RBCs is mostly restricted to the marrow from the ends of the "long" bones-the vertebrae, ribs, and pelvis-with a little produced in the skull. The life cycle of a normal RBC is about 120 days, just four months. But in that short lifetime the RBC makes an astonishing 75,000 round trips between the lungs, heart and cells of the body. Since RBCs do not possess a nucleus, they are unable to repair or synthesize new cellular components and eventually they wear out. When that happens, most aging RBCs are pulled out of circulation by specialized white blood cells called macrophages within the liver, spleen, and lymph nodes. The macrophages engulf RBCs, "digest" them and release some of their components to be recycled within the body. As old RBCs are broken down and their components re-utilized, the bone marrow is constantly at work producing new RBCs. In a healthy human being, this is a dynamic and continuous process.

COMPOSITION OF THE BLOOD

Illustration of blood composition.

When a sample of blood is spun in a centrifuge, the cells and cell fragments are separated from the liquid intercellular matrix. Because the formed elements are heavier than the liquid matrix, they are packed in the bottom of the tube by the centrifugal force. The light yellow colored liquid on the top is the plasma, which accounts for about 55 percent of the blood volume and red blood cells is called the hematocrit,or packed cell volume (PCV). The white blood cells and platelets form a thin white layer, called the "buffy coat", between plasma and red blood cells.

Erythrocytes (red blood cells)

Erythrocytes, or red blood cells, are the most numerous of the formed elements. Erythrocytes are tiny biconcave disks, thin in the middle and thicker around the periphery. The shape provides a combination of flexibility for moving through tiny capillaries with a maximum surface area for the diffusion of gases. The primary function of erythrocytes is to transport oxygen and, to a lesser extent, carbon dioxide.

National Cancer Institute / NIH

Erythropoietin

Glycoprotein hormone, secreted chiefly by the KIDNEY in the adult and the LIVER in the FETUS, that acts on erythroid stem cells of the BONE MARROW to stimulate proliferation and differentiation.

Epoetin Alfa

A recombinant glycosylated form of erythropoietin which stimulates the differentiation and proliferation of erythroid precursors. It is used for the treatment of ANEMIA associated with CHRONIC RENAL FAILURE in dialysis and predialysis patients.

Receptors, Erythropoietin

Cell surface proteins that bind erythropoietin with high affinity and trigger intracellular changes influencing the behavior of cells.

National Center for Biotechnology Information, U.S. National Library of Medicine


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